// addrspace.cc 
//	Routines to manage address spaces (executing user programs).
//
//	In order to run a user program, you must:
//
//	1. link with the -N -T 0 option 
//	2. run coff2noff to convert the object file to Nachos format
//		(Nachos object code format is essentially just a simpler
//		version of the UNIX executable object code format)
//	3. load the NOFF file into the Nachos file system
//		(if you haven't implemented the file system yet, you
//		don't need to do this last step)
//
// Copyright (c) 1992-1993 The Regents of the University of California.
// All rights reserved.  See copyright.h for copyright notice and limitation 
// of liability and disclaimer of warranty provisions.

#include "copyright.h"
#include "system.h"
#include "addrspace.h"
#include "noff.h"
#include "table.h"
#include "ProcessTable.h"


extern "C" { int bzero(char *, int); };

Table::Table(int s) : map(s), table(0), lock(0), size(s) {
    table = new void *[size];
    lock = new Lock("TableLock");
}

Table::~Table() {
    if (table) {
	delete table;
	table = 0;
    }
    if (lock) {
	delete lock;
	lock = 0;
    }
}

void *Table::Get(int i) {
    // Return the element associated with the given if, or 0 if
    // there is none.

    return (i >=0 && i < size && map.Test(i)) ? table[i] : 0;
}

int Table::Put(void *f) {
    // Put the element in the table and return the slot it used.  Use a
    // lock so 2 files don't get the same space.
    int i;	// to find the next slot

    lock->Acquire();
    i = map.Find();
    lock->Release();
    if ( i != -1)
	table[i] = f;
    return i;
}

void *Table::Remove(int i) {
    // Remove the element associated with identifier i from the table,
    // and return it.

    void *f =0;

    if ( i >= 0 && i < size ) {
	lock->Acquire();
	if ( map.Test(i) ) {
	    map.Clear(i);
	    f = table[i];
	    table[i] = 0;
	}
	lock->Release();
    }
    return f;
}

//----------------------------------------------------------------------
// SwapHeader
// 	Do little endian to big endian conversion on the bytes in the 
//	object file header, in case the file was generated on a little
//	endian machine, and we're now running on a big endian machine.
//----------------------------------------------------------------------

static void 
SwapHeader (NoffHeader *noffH)
{
	noffH->noffMagic = WordToHost(noffH->noffMagic);
	noffH->code.size = WordToHost(noffH->code.size);
	noffH->code.virtualAddr = WordToHost(noffH->code.virtualAddr);
	noffH->code.inFileAddr = WordToHost(noffH->code.inFileAddr);
	noffH->initData.size = WordToHost(noffH->initData.size);
	noffH->initData.virtualAddr = WordToHost(noffH->initData.virtualAddr);
	noffH->initData.inFileAddr = WordToHost(noffH->initData.inFileAddr);
	noffH->uninitData.size = WordToHost(noffH->uninitData.size);
	noffH->uninitData.virtualAddr = WordToHost(noffH->uninitData.virtualAddr);
	noffH->uninitData.inFileAddr = WordToHost(noffH->uninitData.inFileAddr);
}

//----------------------------------------------------------------------
// AddrSpace::AddrSpace
// 	Create an address space to run a user program.
//	Load the program from a file "executable", and set everything
//	up so that we can start executing user instructions.
//
//	Assumes that the object code file is in NOFF format.
//
//	"executable" is the file containing the object code to load into memory
//
//      It's possible to fail to fully construct the address space for
//      several reasons, including being unable to allocate memory,
//      and being unable to read key parts of the executable.
//      Incompletely consretucted address spaces have the member
//      constructed set to false.
//----------------------------------------------------------------------

AddrSpace::AddrSpace(OpenFile *executable) : fileTable(MaxOpenFiles) {
    NoffHeader noffH;
    unsigned int i, size;
    spaceLock = new Lock("Stack Map Lock");
    processId = new int;

    // Don't allocate the input or output to disk files
    //fileTable.Put(0);
    //fileTable.Put(0);

    executable->ReadAt((char *)&noffH, sizeof(noffH), 0);
    if ((noffH.noffMagic != NOFFMAGIC) && 
		(WordToHost(noffH.noffMagic) == NOFFMAGIC))
    	SwapHeader(&noffH);
    ASSERT(noffH.noffMagic == NOFFMAGIC);

	codeDataPages=new int;

    size = noffH.code.size + noffH.initData.size + noffH.uninitData.size ;
	(*codeDataPages)= divRoundUp(size, PageSize);
    numPages = (*codeDataPages) + divRoundUp(UserStackSize,PageSize);
	stackMap = new BitMap(numPages-(*codeDataPages));
                                                // we need to increase the size
						// to leave room for the stack
	machine->pageTableSize = numPages;
    size = numPages * PageSize;

    ASSERT(numPages <= NumPhysPages);		// check we're not trying
						// to run anything too big --
						// at least until we have
						// virtual memory

    DEBUG('a', "Initializing address space, num pages %d, size %d\n", 
					numPages, size);
// first, set up the translation 
    pageTable = new TranslationEntry[numPages];
    for (i = 0; i < numPages; i++) {
	pageTable[i].virtualPage = i;	// for now, virtual page # = phys page #
	pageTable[i].physicalPage = PhysicalMemoryMap->Find();
	//pageTable[i].physicalPage = -1;
	pageTable[i].valid = true;
	pageTable[i].use = false;
	pageTable[i].dirty = false;
	pageTable[i].readOnly = false;  // if the code segment was entirely on 
					// a separate page, we could set its 
					// pages to be read-only
    }
    
// zero out the entire address space, to zero the unitialized data segment 
// and the stack segment
    //bzero(machine->mainMemory, size);

// then, copy in the code and data segments into memory

	int vaddr=noffH.code.virtualAddr;
	int* paddr = new int;
	unsigned int vpn;
    while (noffH.code.size > 0) {
		vaddr=noffH.code.virtualAddr;
		vpn=vaddr/PageSize;
		if(vpn>=0&&(unsigned int)vpn<numPages)
		{
			translate(vaddr,paddr,false);
			DEBUG('a', "Initializing code segment, at 0x%x, size %d\n", 
				noffH.code.virtualAddr, noffH.code.size);
			executable->ReadAt(&(machine->mainMemory[*paddr]),
				PageSize, noffH.code.inFileAddr);
		}
		else
		{
			DEBUG('a',"OH GOD, YOU BROKE IT\n");
			ASSERT(FALSE);
		}
		noffH.code.size-=PageSize;
		noffH.code.inFileAddr+=PageSize;
		noffH.code.virtualAddr+=PageSize;
    }

    while (noffH.initData.size > 0) {
		vaddr=noffH.initData.virtualAddr;
		vpn=vaddr/PageSize;

		if(vpn>=0&&(unsigned int)vpn<numPages)
		{
			translate(vaddr,paddr,false);
			DEBUG('a', "Initializing data segment, at 0x%x, size %d\n", 
				noffH.initData.virtualAddr, noffH.initData.size);
			executable->ReadAt(&(machine->mainMemory[*paddr]),
				PageSize, noffH.initData.inFileAddr);
		}
		else
		{
			DEBUG('a',"OH GOD, YOU BROKE IT\n");
			ASSERT(FALSE);
		}
		noffH.initData.size-=PageSize;
		noffH.initData.inFileAddr+=PageSize;
		noffH.initData.virtualAddr+=PageSize;
		
    }

	while (noffH.uninitData.size > 0) {
		vaddr=noffH.uninitData.virtualAddr;
		vpn=vaddr/PageSize;

		if(vpn>=0&&(unsigned int)vpn<numPages)
		{
			translate(vaddr,paddr,false);
			DEBUG('a', "Initializing data segment, at 0x%x, size %d\n", 
				noffH.uninitData.virtualAddr, noffH.uninitData.size);
			executable->ReadAt(&(machine->mainMemory[*paddr]),
				PageSize, noffH.uninitData.inFileAddr);
		}
		else
		{
			DEBUG('a',"OH GOD, YOU BROKE IT\n");
			ASSERT(FALSE);
		}
		noffH.uninitData.size-=PageSize;
		noffH.uninitData.inFileAddr+=PageSize;
		noffH.uninitData.virtualAddr+=PageSize;
		
    }
	
//*(currentThread->processId) = processTable->addProcess(currentThread->space,currentThread);

}

//----------------------------------------------------------------------
// AddrSpace::~AddrSpace
//
// 	Dealloate an address space.  release pages, page tables, files
// 	and file tables
//----------------------------------------------------------------------

AddrSpace::~AddrSpace()
{
    delete pageTable;
}

//----------------------------------------------------------------------
// AddrSpace::InitRegisters
// 	Set the initial values for the user-level register set.
//
// 	We write these directly into the "machine" registers, so
//	that we can immediately jump to user code.  Note that these
//	will be saved/restored into the currentThread->userRegisters
//	when this thread is context switched out.
//----------------------------------------------------------------------

void
AddrSpace::InitRegisters()
{
    int i;

    for (i = 0; i < NumTotalRegs; i++)
	machine->WriteRegister(i, 0);

    // Initial program counter -- must be location of "Start"
    machine->WriteRegister(PCReg, 0);	

    // Need to also tell MIPS where next instruction is, because
    // of branch delay possibility
    machine->WriteRegister(NextPCReg, 4);

   // Set the stack register to the end of the address space, where we
   // allocated the stack; but subtract off a bit, to make sure we don't
   // accidentally reference off the end!
    machine->WriteRegister(StackReg, numPages * PageSize - 16);
    DEBUG('a', "Initializing stack register to %x\n", numPages * PageSize - 16);
}

//----------------------------------------------------------------------
// AddrSpace::SaveState
// 	On a context switch, save any machine state, specific
//	to this address space, that needs saving.
//
//	For now, nothing!
//----------------------------------------------------------------------

void AddrSpace::SaveState() 
{
	printf("or here?\n");
	#ifndef NETWORK
	for(int i = 0;i<NumPhysPages;i++)
	{
		IntStatus oldLevel = interrupt->SetLevel(IntOff);
		machine->tlb[i].valid=false;
		interrupt->SetLevel(oldLevel);
	}
	#endif
}

//----------------------------------------------------------------------
// AddrSpace::RestoreState
// 	On a context switch, restore the machine state so that
//	this address space can run.
//
//      For now, tell the machine where to find the page table.
//----------------------------------------------------------------------

void AddrSpace::RestoreState() 
{
    machine->pageTable = pageTable;
    machine->pageTableSize = numPages;
}

//----------------------------------------------------------------------
//AddrSpace::Translate
//	Translates from virtual addresses to physical address
//----------------------------------------------------------------------
ExceptionType
AddrSpace::translate(int virtAddr, int* physAddr, bool writing)
{
    int i;
    unsigned int vpn, offset;
    TranslationEntry *entry;
    unsigned int pageFrame;

    DEBUG('a', "\tTranslate 0x%x, %s: ", virtAddr, writing ? "write" : "read");

    // we must have either a TLB or a page table, but not both!
   // ASSERT(tlb == NULL || pageTable == NULL);	
   // ASSERT(tlb != NULL || pageTable != NULL);	

// calculate the virtual page number, and offset within the page,
// from the virtual address
    vpn = (unsigned) virtAddr / PageSize;
    offset = (unsigned) virtAddr % PageSize;
    
	if (vpn >= machine->pageTableSize) {
	    DEBUG('a', "virtual page # %d too large for page table size %d!\n", 
			virtAddr, machine->pageTableSize);
	    return AddressErrorException;
	} else if (!pageTable[vpn].valid) {
	    DEBUG('a', "virtual page # %d too large for page table size %d!\n", 
			virtAddr, machine->pageTableSize);
	    return PageFaultException;
	}
	entry = &pageTable[vpn];
    if (entry->readOnly && writing) {	// trying to write to a read-only page
	DEBUG('a', "%d mapped read-only at %d in TLB!\n", virtAddr, i);
	return ReadOnlyException;
    }
    pageFrame = entry->physicalPage;

    // if the pageFrame is too big, there is something really wrong! 
    // An invalid translation was loaded into the page table or TLB. 
    if (pageFrame >= NumPhysPages) { 
	DEBUG('a', "*** frame %d > %d!\n", pageFrame, NumPhysPages);
	return BusErrorException;
    }
    entry->use = TRUE;		// set the use, dirty bits
    if (writing)
	entry->dirty = TRUE;
    *physAddr = pageFrame * PageSize + offset;
    //ASSERT((*physAddr >= 0) && ((*physAddr + size) <= MemorySize));
    DEBUG('a', "phys addr = 0x%x\n", *physAddr);
    return NoException;
}

void AddrSpace::ClearStackPage(int stackPage)
{
	if(pageTable[stackPage+*codeDataPages].valid==true)
	{
		stackMap->Clear(stackPage);
		PhysicalMemoryMap->Clear(pageTable[stackPage+*codeDataPages].physicalPage);
	}
}

void AddrSpace::ClearProcessPages()
{
	for(int i=0;i<numPages;i++)
	{
		PhysicalMemoryMap->Clear(pageTable[i].physicalPage);
	}
}
